It's the value that you defined when you installed Excel/Office, and it is
setup in the registry.
You could re-install Excel, or change the registry. You would need to get
the GUID of the product, and find that in the key
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products
and it would be the Value RegOwner under that GUID. If you take this route,
backup the registry. I don't recommend it, and be it on your own head, I
might ave the wrong key, I have never done it myself, but I am sure it can
be done.
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HTH
Bob
(there's no email, no snail mail, but somewhere should be gmail in my addy)